At present, false floors are constructed of rectangular slabs or tiles which are supported on packing blocks or column supports set under the four corners of each slab or tile. Typically, these slabs or tiles are pre-cast reinforced concrete members or are pressed steel members filled with concrete or particle board. Unless the floor or roof above which the false floor is located is planar and the column supports are of uniform height, the slabs or tiles are not supported on all four supports simultaneously. Planar floors and uniform column supports, however, are rare and either the slabs or tiles rock about the pivot provided by two of the supports, or each slab has to be supported on adjustable jacks at each corner or has to be carefully packed to ensure that it is supported evenly on all four supports. Rocking slabs produce an unsatisfactory false floor. Careful jacking or packing at each support, however, adds considerably to the cost of the installation of the false floor.
To overcome this problem it has been proposed to use rectangular tiles or slabs which can flex or deform about a diagonal of the tile to ensure that all the corners of each of the two triangular sub-tiles rest upon a pedestal or support for the false floor. For example, the specification of French patent No. 2,294,293 discloses rectangular tiles which are constructed as triangular sub-tiles, hinged together. Each sub-tile has the shape of a right-angled triangle. The sub-tiles are joined together by a flexible material embedded within the sub-tiles, so that the hypotenuse of one sub-tile is adjacent to, but spaced a small distance from the hypotenuse of the other sub-tile. The flexible material acts as a hinge between the two sub-tiles, allowing a small inclination of the plane of one sub-tile relative to the plane of the other sub-tile.
Several other examples of a deformable tile have been described in the specification of International patent application No. PCT/AU85/00270, which was published as WIPO publication No. W086/02969. Each rectangular, concrete tile or slab illustrated and described in that specification is provided with a line of weakness in the tile or slab, located along a diagonal of the rectangle. The line of weakness may be a groove formed in the concrete of the tile or slab or in a reinforcing steel pan of the tile or slab. The inclusion of a hinge connecting two triangular sub-tiles is also suggested in WIPO publication No. W086/02969.